﻿function foo (a)
	print("foo", a)
	return coroutine.yield(2*a)
end
     
co = coroutine.create(function (a,b)
    print("co-body", a, b)
    local r = foo(a+1)
    print("co-body", r)
    local r, s = coroutine.yield(a+b, a-b)
    print("co-body", r, s)
    return b, "end"
end)
     
print("main", coroutine.resume(co, 1, 10))
print("main", coroutine.resume(co, "r"))
print("main", coroutine.resume(co, "x", "y"))
print("main", coroutine.resume(co, "x", "y"))